The correct humidifier filter replacement for your Gibson unit is shown below. This is a cut-to-fit foam material that measures 6" x 65" x 3/8". This can be trimmed to the desired size to achieve the proper fit for your system. This efficient foam will allow proper operation of your humidifier unit, keeping it clean from mineral build-up and allow fresh, humidified air into your home to improve your indoor comfort and air quality during dry months. Contact U.S. Home Filter for all your replacement HVAC filters.